Institute of Cardiovascular and Medical Sciences, University of Glasgow, United Kingdom.
Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Brazil.
J Am Heart Assoc. 2018 Jun 15;7(12):e009388. doi: 10.1161/JAHA.118.009388.
NADPH Oxidase 5 (Nox5) is a calcium-sensitive superoxide-generating Nox. It is present in lower forms and higher mammals, but not in rodents. Nox5 is expressed in vascular cells, but the functional significance remains elusive. Given that contraction is controlled by calcium and reactive oxygen species, both associated with Nox5, we questioned the role of Nox5 in pro-contractile signaling and vascular function.
Transgenic mice expressing human Nox5 in a vascular smooth muscle cell-specific manner (Nox5 mice) and , an arthropod model that expresses Nox5 endogenoulsy, were studied. Reactive oxygen species generation was increased systemically and in the vasculature and heart in Nox5 mice. In Nox5-expressing mice, agonist-induced vasoconstriction was exaggerated and endothelium-dependent vasorelaxation was impaired. Vascular structural and mechanical properties were not influenced by Nox5. Vascular contractile responses in Nox5 mice were normalized by -acetylcysteine and inhibitors of calcium channels, calmodulin, and endoplasmic reticulum ryanodine receptors, but not by GKT137831 (Nox1/4 inhibitor). At the cellular level, vascular changes in Nox5 mice were associated with increased vascular smooth muscle cell [Ca], increased reactive oxygen species and nitrotyrosine levels, and hyperphosphorylation of pro-contractile signaling molecules MLC20 (myosin light chain 20) and MYPT1 (myosin phosphatase target subunit 1). Blood pressure was similar in wild-type and Nox5 mice. Nox5 did not amplify angiotensin II effects. In , gastrointestinal smooth muscle contraction was blunted by Nox5 silencing, but not by VAS2870 (Nox1/2/4 inhibitor).
Nox5 is a pro-contractile Nox isoform important in redox-sensitive contraction. This involves calcium-calmodulin and endoplasmic reticulum-regulated mechanisms. Our findings define a novel function for vascular Nox5, linking calcium and reactive oxygen species to the pro-contractile molecular machinery in vascular smooth muscle cells.
NADPH 氧化酶 5（Nox5）是一种钙敏感性超氧化物生成的 Nox。它存在于低等生物和高等哺乳动物中，但不存在于啮齿动物中。Nox5 在血管细胞中表达，但功能意义尚不清楚。鉴于收缩受钙和活性氧物质的控制，而这两者都与 Nox5 有关，我们质疑 Nox5 在促收缩信号和血管功能中的作用。
研究了以血管平滑肌细胞特异性方式表达人 Nox5 的转基因小鼠（Nox5 小鼠）和表达内源性 Nox5 的节肢动物模型。Nox5 小鼠系统和血管中活性氧物质的生成增加，心脏也增加。在 Nox5 表达的小鼠中，激动剂诱导的血管收缩被夸大，内皮依赖性血管舒张受损。血管结构和机械性能不受 Nox5 的影响。Nox5 小鼠的血管收缩反应通过 N-乙酰半胱氨酸和钙通道、钙调蛋白和内质网肌醇 1,4,5-三磷酸受体抑制剂得到正常化，但不受 GKT137831（Nox1/4 抑制剂）的影响。在细胞水平上，Nox5 小鼠的血管变化与血管平滑肌细胞[Ca]增加、活性氧物质和硝基酪氨酸水平增加以及促收缩信号分子 MLC20（肌球蛋白轻链 20）和 MYPT1（肌球蛋白磷酸酶靶亚单位 1）的过度磷酸化有关。野生型和 Nox5 小鼠的血压相似。Nox5 并没有放大血管紧张素 II 的作用。在，Nox5 的沉默削弱了胃肠道平滑肌的收缩，但 VAS2870（Nox1/2/4 抑制剂）没有。
Nox5 是一种促收缩的 Nox 同工酶，在氧化还原敏感的收缩中很重要。这涉及钙-钙调蛋白和内质网调节的机制。我们的发现定义了血管 Nox5 的一个新功能，将钙和活性氧物质与血管平滑肌细胞中的促收缩分子机制联系起来。
